Cold cathode discharge display apparatus

ABSTRACT

In a cold cathode discharge display apparatus of the class comprising a first electrode, a plurality of second electrodes confronting the first electrode and an envelope containing the first and second electrodes and filled with a luminous inert gas, at least a portion of the envelope being transparent, there are provided an insulative spacer disposed between the first and second electrodes and formed with a plurality of discrete discharge cells, a plurality of starting electrodes respectively provided for the discharge cells between the first and second electrodes, and a plurality of resistors respectively connected to the second electrodes.

United States Patent Sasaki et al.

COLD CATHODE DISCHARGE DISPLAY APPARATUS Inventors: Rentaro Sasaki; Akinori Watanabe,

both of Takasaki; Tatsuo Cgasawara, Tokyo; Satoshi Watanabe, Gyoda, all of Japan Assignees: Oki Electric Industry Company Ltd.; Okaya Electric Company Ltd., both of Tokyo, Japan Filed: Sept. 29, 1972 Appl. No.: 293,335

U.S. Cl. 313/188, 315/58 Int. Cl. H0lj 61/30 Field of Search..... 313/188, 109.5; 315/169 R,

vRelerences Cited UNITED STATES PATENTS 6/1971 Tech ..3l5/169R 11/1971 Caras ..3l5/169R [111 3,803,439 [451 Apr.9, 1974 3,315,! 15 4/1967 Maloney 313/1095 3,629,638 12/1971 Veron et a1. 315/169 R 3,336,499 8/1967 OMeara 313/188 Primary Examiner-James W. Lawrence Assistant Examiner-B. C. Anderson Attorney, Agent, or Firm-Chittick, Thompson &

Pfund [5 7] ABSTRACT In a cold cathode discharge display apparatus of the class comprising a first electrode, a plurality of second electrodes confronting the first electrode and an envelope containing the first and second electrodes and filled with a luminous inert gas, at least a portion of the envelope being transparent, there are provided an insulative spacer disposed between the first and second electrodes and formed with a plurality of discrete discharge cells, a plurality of starting electrodes respectively provided for the discharge cellsbetween the firstand second electrodes, and a plurality of resistors respectively connected to the second electrodes.

9 Claims, 9 Drawing Figures PATENTEBAPR 9 i974 SHiiET 5 (IF 5 F/GQB W A /AI COLD CATHODE DISCHARGE DISPLAY APPARATUS BACKGROUND OF THE INVENTION This invention relates to a cold cathode electrode discharge display apparatus and more particularly to such display apparatus having memory function.

In a conventional cold cathode discharge display apparatus, an electric discharge is established between a pair of opposed electrodes in an envelope filled with an inert'gas such as neon or argon gas and the light caused by the discharge is used to desplay a desired pattern.

In the commercial cold cathode discharge device sold under the trade marks of Elfin and Planitron a plurality of display units, each consisting of a plurality of segment electrodes and a counter electrode disposed to oppose the segment electrodes with a predetermined spacing therebetween, are disposed side by side in the same envelope. Such a display device is used to display patterns of a plurality of digits by selectively operating the display units on the time division basis at such a high speed that does not cause a flicker. 7 However, because such' a display device lacks memory function it is necessary to provide an independent memory device thereby increasing the cost and complicating the construction of the display device.

Further, it is necessary to increase the frequency of the time division signal when the number of digits or orders of magnitude is increased.

SUMMARY OF THE INVENTION Accordingly, it is an object of this invention to provide an improved cold cathodedischarge display .ap'paratus having a memory function so that it' is possible to continuously display a selected pattern without using any external memory device.

Another object of this invention is to provide a novel cold cathode discharge memory device capable of displaying at a high speed a plurality of patterns of large digits on the time division basis with a simplified driving circuit. Still another object of this invention is to provide an improved cold cathode discharge display apparatus including anode electrodes and anode resistors integrally formed therewith. I

Yet another object of this invention is to provide a cold cathode discharge display apparatus including a plurality of anodes and anode resistors associated therewith which is simple and compact in construction and can be arranged at a high density.

According to this invention, these and other objects can be accomplished by providing a cold cathode discharge display apparatus of the class-comprising a first electrode acting as the cathode electrode, a plurality of second electrodes confronting the first electrode and acting as anode electrodes and anenvelope containing the first and second electrodes and filled with a luminous inert gas and wherein a portion of the envelope is transparent, characterized in that there are provided an connected to the second electrodes.

According to one embodiment of this invention the anode resistors are contained in the perforations of an anode substrate placed between the spacer containing the starting electrode and a transparent substrate.

According to a modified embodiment of this invention, the anode substrate comprises a rectangular block shaped resistor and one surface thereof is divided into a plurality of projections arranged in a matrix by means of a plurality of grooves intersecting with each other. This metal films are coated on the upper surfaces of the projections to form discrete anode electrodes.

An anode voltage which decreases to a lower level after a predetermined interval is applied to a selected anode electrode concurrently with the application of a starting voltage upon a corresponding starting electrode whereby an electric discharge is established between the selected anode electrode and starting electrode and then the discharge is transferred automatically to the selected electrode and the first or cathode electrode. This discharge is sustained after disappearance of the starting voltage whereby the display apparatus manifests by itself a memory function.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be more fully understood from the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 is an exploded perspective view showing one embodiment of the novel cold cathode discharge display apparatus embodying the invention;

' FIG. 2 is a plan view showing one example of a start- FIG. 7 is an exploded perspective view of a modified cold cathode discharge display apparatus employing a modified construction of the anode electrodes and anode resistors;

FIG. 8 shows an enlarged perspective view of one anode substrate shown in FIG. 7; and i FIG. 9 shows a sectional view of the anode substrate shown in FIG. 8 taken along a line IX IX.

DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the novel cathode discharge display apparatus 1 comprises an upper substrate 2, a. lower substrate 3 which are made" of transparent electric insulator sheets such as glass sheets, a cathode substrate 4, a first spacer 5 a'starting electrode substrate 6, a second spacer 7 and an anode substrate 8, the substrates 4, 6 and 8 and spacers 5 and 7 being disposed between the upper and lower substrates 2 and 3 and respectively provided with a plurality of groups of perforations 9 which are arranged in matrixes. Perforations of corresponding groups of various elements are aligned in the vertical direction as viewed in FIG. 1. On the opposite ends ofthe lower surfacev (which faces the cathode substrate 4) of the anode sub strate 2 are formed a plurality of starting electrode terminals and a cathode terminal 11 which are connected to electrodes to be described later and are formed by electroplating, vacuum deposition or any other suitable method. The upper surface of the cathode substrate 5 which faces the upper substrate 2 and the entire inner walls of the perforations 9 of the cathode substrate 5 are coated with a thin metal layer 12 which functions as the cathode electrode and is formed by a similar method to that described for forming terminals l0 and 11. A

The inner walls of the respective perforations 9 of the starting electrode substrate 6 are lined with through hole platings which are used to act as the starting electrode 13 and are connected to terminals 14 as shown in FIG. 2, the terminals 14 being formed on the upper and lower surfaces of the substrate 6 at the opposite ends thereof by print wiring or the like technique. The anode substrate 8 comprises an insulator sheet and the perforations thereof are packed with solid state resistors 15 of compressed powders of glass or ceramics, as shown in FIG. 3. The surfaces of the resistors 15 which face the second spacer 7 are plated with nickel or the like metal and these plated films 16 are used as the anodes 16. The opposite surfaces of the resistors 15 are connected to independent thin sheets 17a through 17d which are provided for respective groups of the perforations and are made of a material, such as 42-6 alloy, having substantially the same coefficient of thermal expansion as the lower substrate 3 of glass or ceramic, each thin sheet covering each group of the perforations. Around the periphery of the insulative lower substrate 3 are formed a plurality of starting electrode terminals 18 adapted to be connected to terminals 14 of the starting electrode substrate 6 and a plurality of anode terminals 19a through 19 d adapted to be connected to thin sheets 17a through 17d on the anode substrate 8.

These substrates are superposed one upon the other to form a lamination as shown in FIG. 4 and the periphery of the lamination is sealed with frit glass or the like. Thus, the upper and lower substrates 2 and 3 are used to form a portion of the envelope. Thereafter, the interior of the envelope is evacuated and then filled with an inert gas such as neon gas, argon gas or the like thereby completing a cold cathode dischargev display apparatus.

The equivalent circuit of this cold cathode discharge display apparatus is shown in FIG. 5. More particularly, there are provided a matrix driving member 20, and high resistance protective resistors 21a through 2ln which are connected between the output terminals of the matrix driving member and respective starting electrode terminals 14a through 14n of the display apparatus which includes four display units 220 through 22d. The spacings between the cathode electrode 12 and the starting electrode 13 and between the starting electrode 13 and the anode electrode 16 are set to satisfythe following conditions:

A. The breakdown or discharge initiating voltage between the anode electrode 16 and the cathode electrode 12 is higher than that between the anode electrode 16 and the starting electrode 13.

B. The discharge sustaining voltage between the anode electrode 16 and the cathode electrode 12 is lower than that between the anode electrode 16 and the starting electrode 13. Typical values of these voltages are as follows:

Breakdown voltage between anode 16 and cathode 12 200V,

Sustaining voltage between anode l6 and cathode 12 V,

Breakdown voltage between anode l6 and starting electrode 13 190V and Sustaining voltage between anode l6 and starting electrode 13 180V.

In the following, the operation of the cold cathode discharge display apparatus will be described in detail.

Upon application of an input signal, the matrix driving member 20 transforms this signal to into a negative voltage (3OV) and applies this voltage to a starting electrode terminal 14a, for example, corresponding to the pattern information contained in the input signal. Responsive to the output signal from the matrix driving member 20 an anode voltage is applied to the anode terminal 19a of the first display unit 22a which is a little smaller than the breakdown voltage (200V) between anode 16 and cathode l2 and decreases after a predetermined interval to a voltage slightly higher than the sum of the anode voltage and the voltage (30V) which is applied upon the starting electrode. A typical example of the waveform of the anode voltage is shown in FIG. 6 wherein the voltage decreases to V from V after a predetermined interval. Then the voltage between the selected starting electrode 13a and the anode electrode 16 is increased to 210V which is higher than the breakdown voltage (200V) between the anode electrode 16 and the cathode electrode 12. As a result, an electric discharge is established between the starting electrode 13a and the anode electrode 16 which is connected to the anode terminal 19a via resistor 15a, whereby only the portion between these electrodes 13a and 16 luminescences. Since the discharge sustaining voltage between anode electrode 16 and the cathode electrode 12 is set to 140V which is lower than the discharge sustaining voltage 180V between the anode electrode 16 and the starting electrode 13, the discharge established as above described will be transferred between the anode electrode 16 and the cathode electrode 12. As the discharge transfers in this manner, the discharge current increases from an extremely small value determined by the high resistance protective resistors 21a through 21n connected to the starting electrodes 13a through 13n to a large value, and this increased current flows through directly grounded cathode electrode 12. As a result, the anode voltage is decreased .to about 140V, or the discharge sustaining voltage between the anode and cathode electrodes due to the voltage drop across resistor 15a, thus sustaining the discharge between the anode and cathode electrodes. In this manner, the discharge transfers automatically from between the anode and starting electrodes to between the anode and cathode electrodes and thereafter the discharge is maintained independently of the input voltage thereby manifesting memory function.

To display a pattern on the second display unit 22b, the anode voltage shown in FIG. 6 is impressed upon the anode terminal 19b concurrently with the application of a selection signal (-30V) upon selected ones of starting electrodes 13a through l3n corresponding to the pattern to be displayed. Then, the discharge is established between the selected one of the starting electrodes 130 through 13n and anode l6 and the discharge is transferred to and sustained between the anode electrode l6 and the cathode electrode 12. The discharge is sustanined in perforation 9 shown in FIG. 4 and provides the desired pattern through transparent upper substrate 2. In other words, perforations 9 constitute discharge cells and the input signal (30V) is supplied to starting electrodes 13a through l3n whereas the anode voltage selects the display position of the pattern or the digit displayed. Accordingly, by impressing the anode voltage successively upon the selected anode terminal corresponding to the input signal it is possible to continuously display a desired pattern at the requisite position without using any memory device.

With the above described connection, where the starting electrode 13b of the second display unit 22b is selected the selection signal (-3OV) is also applied to the not operating starting electrode 13b of the first display unit 22a which is now being used to display the pattern but the first display unit 22a will not be caused to operate erroneously by the pattern selection signal for the other digit because the anode voltage of the first display unit has been .decreased to a value below the breakdown voltage (190V) between the anode electrode and the starting electrode. However, it is essential to make sufficiently wide the peak of the anode voltage so that the anode voltage will not be decreased until all cathode electrodes selected by the selection signal (-3OV) discharge.

If the anode voltage is sequentially applied to the anode terminals of respective display unit it is possible to sequentially shift the displayed pattern along successive display units without using any external memory device. With this cold cathode discharge display apparatus it is also possible to readily erase any display unit without using any external memory device. In the foregoing description, the starting electrode substrate was shown as having printed wirings on the opposite surfaces thereof, it will be clear that such starting electrodes can also be formed by multilayer printing technique.

In a modified embodiment shown in FIGS; 7, 8 and 9 the andoe substrate 8 shown in the previous embodiment is divided into a plurality of anode substrates 8a through 8d, one for each display unit. As best shown in FIGS. 8 and 9, each anode substrate, for example 8a comprises a rectangular block shaped resistor and the upper surface thereof is divided into a plurality of projections 25a through 25n by means of a plurality of grooves intersecting with each other at right angles. The anode electrodes 16 are formed on respective projections by applying nickel platings or the like. As before, these plurality of anode electrodes are disposed in a matrix corresponding to the matrix of perforations of the cathode substrate 4 included in one display unit. The opposite surfaces of the resistors 25 are coated with thin sheets 17a through 17d of a material such as 42-6 alloy having substantially the same coefficient of thermal expansion as that of the lower substrate 3 of glass or ceramic. With this modification, as the resistor projections 25a through 25n, anode electrodes 16 and thin sheets 17a through 17d are interconnected through surface contacts of high reliability. Further, this modification is more advantageous than the previous embodiment in that the construction of the anodes and anode resistors can be simplified greatly.

It will be clear that the invention provides an improved cold cathode discharge display apparatus capable of providing continuous display of patterns without using any external memory device. Moreover as the display apparatus itself has a memory function it is not necessary to drive it on the time division basis especially when the display apparatus is constructed to dis,- play a plurality of digits, thereby greatly simplifying the external driving circuit. Further, as the anodeelec trodes and anode resistors are formed integratly not only their construction is simplified but also their reliability is increased. Thus, it is possibleto arrange a plurality of anode electrodes and anode resistors at a high density.

While the invention has been shown and described in terms of some preferred embodiments thereof it will be clear that many changes and modifications will readily occur to one skilled in the art without departing from the true spirit and scope of the invention as defined in the appended claims.

What is claimed is:

1. A cold cathode discharge display apparatus comprising a first electrode, a plurality of second electrodes facing said first electrode, an insulative spacer disposed between said first and second electrodes and'formed with a plurality of discrete discharge cells, discrete starting electrodes provided for each of said discharge cells between said first and second electrodes, a plurality of resistors respectively connected to said second electrodes, and an envelope enclosing above described elements to form an independent discharge device having said first, second and starting electrodes in each of said cells and said cells filled with a luminous inert gas, at least a portion of said envelope for each said cell being transparent. i

2. The display apparatus according to claim 1 which further comprises means for impressing upon the selected one of said second electrodes an anode voltage of a waveform having a first level decreasing to a predetermined level after a predetermined interval and means for applying a starting voltage upon the selected one of said starting electrodes substantially concurrently with the application of said anode voltage corresponding to a pattern tobe displayed, said anode voltage and said starting voltage during said predetermined interval establishing an electric discharge between said selected second electrode and said selected starting electrode and said discharge automatically transferring to between said selected second electrode and said first electrode when said waveform decreases to said predetermined level.

3. The display apparatus according to claim 1 wherein the spacing between said first electrode and said starting electrode and that between said starting electrode and said second electrode are dimensioned such that the breakdown voltage between said first and second electrodes is higher than the breakdown voltage between said starting electrode and said second electrode and that the discharge sustaining voltage between said first and second electrodes is higher than that between said second electrode and said starting electrode.

4. The display apparatus according to claim 1 wherein at least one of said first and second electrodes is overlayed by a transparent insulative substrate which forms a portion of said envelope.

5. The display apparatus according to claim 1 wherein said insulative spacer is provided with a plurality of groups of perforations which are arranged in matrixes and the inner wall of each perforation is lined with a thin metal film acting as said starting electrode.

6. The display apparatus according to claim 1 wherein said second electrodes comprise a rectangular block shaped resistor, a plurality of projections formed on one surface of said resistor by means of a plurality of grooves intersecting with each other at right angles, metal films applied on respective projections and a conductive metal film applied on the opposite surface of said resistor.

7. The display apparatus according to claim 2 wherein said anode voltage has a value a little lower than the breakdown voltage between said first and second electrodes and decreases after a predetermined interval to a value, the sum thereof and the voltage impressed upon said starting electrode being slightly higher than the starting voltage between said second electrode and said starting electrode.

8. The display apparatus according to claim 6 wherein said second electrode comprises an insulative substrate provided with a plurality of groups of perforations which are arranged in matrixes corresponding to the matrixes of said insulative spacer and each perforation is packed with a solid state resistor with a metal film coated on one thereof facing said insulative spacer, said metal film acting as an anode electrode, the opposite ends of said resistors being electrically connected to a common conductive sheet.

9. The display apparatus according to claim 8 wherein said projections and said metal films on said projections are grouped into a plurality of groups and said conductive metal film is applied to each group.

* m it UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION PATENT NO. 3, 803,439 DATED April 9 1974 INVENTOR(S) Rentaro Sasaki; Akinori Watanabe; 'Ia tsuo Ogasawara;

I Satoshi Watanabe it IS certified that BHOT appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In the legend, in item [75] the inventor 5 name "Tatsuo Cgasawara" should be:

Tatsuo Ogasawara Signed and sealed this 24th day of June 1975.

SEAL) Atest:

L C. I IARSHALL DANN RUTH C. MASON Commissioner of Patents and Trademarks Attesting Officer 

1. A cold cathode discharge display apparatus comprising a first electrode, a plurality of second electrodes facing said first electrode, an insulative spacer disposed between said first and second electrodes and formed with a plurality of discrete discharge cells, discrete starting electrodes provided for each of said discharge cells between said first and second electrodes, a plurality of resistors respectively connected to said second electrodes, and an envelope enclosing above described elements to form an iNdependent discharge device having said first, second and starting electrodes in each of said cells and said cells filled with a luminous inert gas, at least a portion of said envelope for each said cell being transparent.
 2. The display apparatus according to claim 1 which further comprises means for impressing upon the selected one of said second electrodes an anode voltage of a waveform having a first level decreasing to a predetermined level after a predetermined interval and means for applying a starting voltage upon the selected one of said starting electrodes substantially concurrently with the application of said anode voltage corresponding to a pattern to be displayed, said anode voltage and said starting voltage during said predetermined interval establishing an electric discharge between said selected second electrode and said selected starting electrode and said discharge automatically transferring to between said selected second electrode and said first electrode when said waveform decreases to said predetermined level.
 3. The display apparatus according to claim 1 wherein the spacing between said first electrode and said starting electrode and that between said starting electrode and said second electrode are dimensioned such that the breakdown voltage between said first and second electrodes is higher than the breakdown voltage between said starting electrode and said second electrode and that the discharge sustaining voltage between said first and second electrodes is higher than that between said second electrode and said starting electrode.
 4. The display apparatus according to claim 1 wherein at least one of said first and second electrodes is overlayed by a transparent insulative substrate which forms a portion of said envelope.
 5. The display apparatus according to claim 1 wherein said insulative spacer is provided with a plurality of groups of perforations which are arranged in matrixes and the inner wall of each perforation is lined with a thin metal film acting as said starting electrode.
 6. The display apparatus according to claim 1 wherein said second electrodes comprise a rectangular block shaped resistor, a plurality of projections formed on one surface of said resistor by means of a plurality of grooves intersecting with each other at right angles, metal films applied on respective projections and a conductive metal film applied on the opposite surface of said resistor.
 7. The display apparatus according to claim 2 wherein said anode voltage has a value a little lower than the breakdown voltage between said first and second electrodes and decreases after a predetermined interval to a value, the sum thereof and the voltage impressed upon said starting electrode being slightly higher than the starting voltage between said second electrode and said starting electrode.
 8. The display apparatus according to claim 6 wherein said second electrode comprises an insulative substrate provided with a plurality of groups of perforations which are arranged in matrixes corresponding to the matrixes of said insulative spacer and each perforation is packed with a solid state resistor with a metal film coated on one thereof facing said insulative spacer, said metal film acting as an anode electrode, the opposite ends of said resistors being electrically connected to a common conductive sheet.
 9. The display apparatus according to claim 8 wherein said projections and said metal films on said projections are grouped into a plurality of groups and said conductive metal film is applied to each group. 